A Tui flight descended unnoticed after the crew became overloaded by the high workload during a ‘go-around’ at Aberdeen airport, according to an official report.
The Boeing 737-800 dropped from the manually flown go-around altitude for around a minute before subsequently climbing, the Air Accidents Investigations Branch (AAIB) found.
The six crew members and all 67 passengers were unharmed in the incident involving a Tui Airways flight from Palma in September 11 last year.
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The AAIB said it was informed two days later that a “serious incident” had occurred.
A report into the incident published on Thursday said: “The aircraft descended for a total of 57 seconds before the climb was re-established.
“It is likely that the crew allowed the aircraft to descend unnoticed having become overloaded by the high workload during the go-around.
“The high workload was due to a combination of factors: the requirements of flying the go-around manoeuvre manually; a larger than expected increase in thrust that led to a high pitch attitude and rate of climb; and the fact that non-standard go-around instructions were issued by ATC [air traffic control].
“Both pilots had experienced significant periods away from flying during the pandemic.”
The AAIB added: “Following this event, safety action was taken by ATC at the airport in relation to go-around procedures; the operator, which issued guidance to its pilots and developed a relevant training package; and by the manufacturer which issued clarification on the behaviour of the autothrust system during go-arounds.”